Dave, My wife and I have a 2005 Fleetwood Bounder with a 5.9l Cummins and Freightliner chassis. Having a/c problems, is this a repair problem for Freightliner, Cummins, or Fleetwood? This is the first time we've had any trouble and would like advice on whether to take it to an rv repair center or a diesel repair service place? Would like a trustworthy and competent shop in the south Florida area. Oh forgot, its the cab a/c not roof a/c. Any suggestions from ya'll will be appreciated. Thanks

Charlie, my suggestion I would go with freighliner. I have mixed thoughts for the othercompany you suggested. You indicated AC problem anything, I can help you with becauseproblem feel will be minor in nature. One thing when you decide to take to service shop,do not let them make any changes with there work order you sign before work is started.If the AC compressor is ok and blowing warm air, make sure they vacuum your AC systemdown to 28 inches of vacuum and shut vacuum pump off and turn the AC gauges off for20 to 30 minutes. If vacuum on system holds than you can put the 134a coolant, systemtakes 1 1/2 to 3 pounds of coolant. Ask Dave, Dave Atherton Retired Cat Mechanic

Thanks Dave, that really clears this up for me. there is a Freightliner service center in Tampa not that far. Also the idea of drawing down the a/c and putting a vacuum in the system to see if it holds rather then using 134a pressure tells a lot without wasting Freon. Great advice and much appreciated. Charlie.

Update on a/c problem. I was told that the compressor cycling module was bad and I need to find out who the manufacturer is. Was told by freightliner they only install the compressor and everything forward of that is the coach builder. So the hunt continues to find out where they hid this module or relay, somewhere around the evaporator I heard. Any other ideas? Thanks in advance. Charlie

Susie and Charlie, feel the reason your AC. Compressor is cycle off and on comes in two fold answer. First sounds like your AC system needs to be vacuum out and holdVacuum for for 20 minutes than recharge with coolant. Reason the high side of your ACCooling system ( red gauge ) has too much pressure and adding additional coolant willCycle AC compressor. The low side of AC ( blue gauge ) 35 to 50. Second the high limintswitch located by AC dryer if bad will cycle compressor often. Do not think you have a big problem and get another opinion on this. Ask Dave, Dave Atherton Retired Cat Mechanic

Dave, sorry I didn't make myself clear. The compressor does not cycle on or off, it stays on all the time causing the system to freeze up. Was told that the cycling module/relay was bad but could not find out where that is located or what the part number would be. I have a call into Fleetwood but no reply yet. Thanks, Charlie

Usually, evaporator freeze up is an indication of low charge. So adding refrigerant might stop the continuous running and return to cycling on and off as necessary. I have not heard of a cycling module. A high pressure, low pressure cutout switch...yes...The system ran bascally continously cooling and to adjust temperature if too cold was to add heat from the cooling system via the "Blend" door. Please let us know more about this module...I am always interested in learning about such things. I spent 30 years as an automotive engineer and we never had a car/truck system with a cycling module, but my experience ended when I retired in 2002.... Even my 2016 Lincoln with dual temp controls for the driver and passenger is just two electrically operated blend doors... not a module that cycled the compressor.

Thanks Phil and Dave, I was told that the high and low pressures were good while the a/c was running but would ice up because the compressor was not cycling off. So maybe the repair shop was talking about the high pressure switch since the coolant was charged, would high pressure cause system ice up? This thing is kicking my butt, and my wallet. Charlie.

It still seems you are low in charge...Did they pull the system down with a vacuum pump and then add refrigerant? If not, you might have quite a bit of air and moisture in the system. Also, it is sometimes necessary to replace the accumulator. Pressures being good for the high side and low side do not indicate if the high side pressure switch is good or not, so did they actually test the switch or just read their manifold gauges? Wish I could contribute more, but seems something is missing here... Good luck!

CharlieAC systems can be a orifice tube design or expansion valve type. On a orifice tube type they use an accumulator with a cycling switch usually mounted on it. That switch cycles the compressor on and off based on the low side pressures. There is also a high pressure cut of located on the high side to protect the system and also a blowoff valve should pressures reach the blowoff point

An expansion valve system uses a valve on the low side line at the evaporater to regulate the low side pressure based on the temperature or the refrigerant leaving the outlet of the evaporater . There systems do not cycle the compressor on and off, the expansion valve just regulates the flow of refrigerant to maintain evaporater temperatures. There usually is a low pressure cut off switch should the system be low in charge or outside temperatures are low enough. These systems also can use a evaporater freeze sensor or switch to turn of the compressor should the evaporator temperature get close to 32 deg F. The switch is sensor is usually located on the evaporator .

Expansion valve systems use a receiver/dryer mounted on the high side line mounted before the expansion valve.

Some systems also use a variable displacement compressor and orifice tube that also does not cycle on and off, it senses the low side pressure and changes the displacement of the compressor to control the.

When you say the system freezes do you mean it stops cooling or you see ice build up somewhere.

I'm heading south and stuck in a snowstorm and wifi is spotty. May not be able to reply back quickly

Phil and Ziggyh, the system has an expansion valve and dryer near the evaporator. Two things I failed to mention is 1; they found that there was to much oil in the lines and that was causing it to freeze up and 2; the high pressure line to the evaporator was old and had deteriorated inside causing another blockage and ice up. The system was drawn down and vacuumed twice and the old line replaced. All major components were replaced including a trinary switch?? The quantity of refrigerant added was listed as 1 which doesn't tell me anything. Was told it was cooling until it actually iced up. I will have all those things checked out, low refrigerant, air and/or moisture and air gap between clutch and compressor. Will update you all when system is finally functional. Thanks to all of you for your input, great to have a resource this rich in experience. Charlie.

Charlie & Susie, here is my take on your problem . AC system will freeze up whenadding too much 134A coolant and even lock up the ACcompressor. Again vacuum down system and let sit for 20/ 30 minutes to see if system will hold vacuum. If it will holdVacuum for 20/30 minute than open the low pressure or blue hose side to allow approx.11/2 pounds of 134a and the reading on the blue gauge should read between 35 & 50psi. Last be sure to disconnect the high limit while charging system than reconnect whenReading on blue gauge falls Within the 35 - 50 psi. Ask Dave , Dave Atherton Retired CatMechanic.